Lubricant



Patented Dec. 17, 1946 UNITED STATES PATENT OFFICE LUBRICANT Murray L. Schwartz, Chicago, Ill., assignor to Standard Oil Company, Chicago, 111., a corporation of In No Drawing. Application December 11, 1945, Serial No. 634,396

20 Claims. (Cl. 252-334) 1 This invention relates to improved lubricants. More particularly it relates to compounded oils which have, in addition to valuable lubricating properties, the property of preventing corrosion of metal surfaces. This specification is a continuation-in-part of my previous application for,

The above observations apply with particular force to engines exposed to severely corrosive atmospheres, such as are encountered, for example, on shipboard, in coastal areas, and in many industrial areas. Engines in military equipment are often subjected to storage in corrosive atmospheres for long periodsof time, for example in transoceanic shipping. Furthermore, the operation of internal combustion engines, especially spark ignition engines, results in the production of gases which corrode variou metal engine parts with which they come in'contact. Particularly corrosive gases are generated in the operation of internal combustion engines upon fuels containing ethyl fluid.

Heretofore it has been proposed to protect metal surfaces from corrosion :by the use of readily removable protective coatings, known as slushing compounds. Slushing compounds are petroleum rust preventives and are usually classified as oils and greases, from the standpoint of appearance, handling and service properties.

Lubricating oils which can also be used as a rust preventive for internal combustion engines, in addition to meeting the usual specifications concerning viscosity, volatility and pour point, must have four main properties:

(3) Ability to be readily applied to and removed from an engine assembly; (4) Ability to neutralize acidic products of combustion in the engine.

It will be apparent that practical specifications based on the above properties can hardly be absolute in nature, but relative standards, represented by certain tests, have :been offered and briefly. Unless otherwise indicated, all tests are carried out upon polished or sand blasted, cold' rolled S. A. E. 1020 steel panels, 2" x 4" x In the humidity test,the steel panels are suspended in an atmosphere of 100% humidity at 100 F. in a special cabinet and the time of initial corrosion of the panels is noted. The humidity cabinet is provided with heating units and thermal regulators for automatic temperature control. A water level of two to three inches is maintained in the bottom of the cabinet to give approximately 100% humidity at all times. Thesteel panels are coated by dipping into the rust preventive material and. are suspended by glass hooks from a glass rod running across the top of the humidity cabinet. To insure that no moisture of condensation comes in contact with the steel panels, stainless steel shields are placed above the panels in such a position that no moisture from the shields can drip on the panels. From 1 to 1.5 complete changes of saturated air per hour are providedin the cabinet. A satisfactory rust preventive should give a minimum of 200 hours protection to the steel panels in the humidity test.

In the test designed to evaluate the effects of the rust preventive composition on metals,

"cleaned lead, copper, magnesium and steel panels, respectively, are immersed to the extent of three-quarters of their area in 160 grams of the rust preventive composition to which 1% of water has been added. After seven days storage at 160 F. the change in weight of each panel is determined. In this test, coupled lead steel panels also are tightly clamped together at an angle of approximately 30 degrees and immersed as described above. Panels of lead, copper and magnesium 2" x 4" x should not show more than 25 mg. change in weight. Likewise .coupled panels of lead-steel should not show more. than 35 mg. change in weight.

The salt water immersion test is designed to measure the ability of rust preventives to protect metal parts against salt air or sea water. In this test the steel panel is dipped in the rust preventive oil, allowed to drain for 24 hours at room temperature, and is then placed in a 3.5% salt solution for twenty hours. At the conclusion of this time the panel must show no evidence of corrosion, staining, or rust.

The hydrobromic acid test is designed to measure the ability of the 'rust preventive oil to neutralize the acidic products of combustion of an internal combustion engine. In this test, the

widely accepted. These tests will be described steel panelisdippedin 0.1% aqueous hydrobromic lubricants.

acid solution momentarily and is then slushed with the rust preventive oil for one minute. The panel is then hung in the laboratory atmosphere for four hours and allowed to drain. At the conclusion of this time the panel must show no corrosion, staining or rust.

Hydrocarbon lubricating oils produced by conventional petroleum refining methods do not possess the combination of properties necessary for service both as lubricants and rust preventives. The observation is common that rusting can occur on steel surfaces which have been coated with the usual straight mineral oil or petrolatums. In order to obtain the desired combination of properties, therehas been a trend toward hydrocarbon oils compounded with various chemical agents, with more or less indifferent success. Experience has shown that often the addition of a given reagent to a hydrocarbonv lubricant results in the improvement of one desired property of the lubricant but exerts a deleteriou effect on one or more of the other desired properties, so that the net result is that it is disadvantageous to add the reagent in question to the lubricant.

Although compounded oils satisfactorily exhibiting the first three properties described above have been produced, they have generally failed in the fourth property.

Accordingly, it is an object of this invention to provide lubricants which can also be used as corrosion reventives. Another object of this invention is to provide a corrosion preventive lubricating composition for internal combustion engines, particularly spark ignition engines. Still another object of this invention is to provide a corrosion preventive lubricatin composition characterized by the ability to neutralize acidic engine combustion products while retaining the other desirable properties of corrosion preventive Additional objects will become apparent as the description of this invention proceeds.

I have found that compositions comprising a small proportion of a castor compound, a preferentially oil-soluble petroleum sulfonate and a hydrocarbon lubricating oil possess the combination of properties desired in corrosion preventive lubricants,

By a castor compound I mean castor oil or its derivatives. Suitable castor compounds include castor oil, castor amide and glycerol monoricinoleate. Although many castor compounds can be used successfully in my corrosion preventive lubricating composition, it is not intended to imply that they are all exactly equivalent in efficacy. In general, about 0.5% to about of castor compound can be used, although somewhat smaller or larger proportions can also be used.

Petroleum sulfonates are soaps of sulfonic acids obtained by the treatment of petroleum oils with strong sulfuric acid, usually fuming sulfuric acid. The preferentially oil-soluble sulfonic acids remain dissolved in the acid treated oil; they are commonly known as mahogany acids. Although a wide variety of mahogany soaps can be used for the purpose of this invention, I have found that they exhibit some variation in efficacy in my corrosion preventive lubricating compositions, depending on their method of preparation.

I have found that-superior mahogany acids and soaps therefrom, for the purpose of this invention, can be produced by treating distillates of from about 50 seconds to about 1000 seconds or higher, and preferably from about 200 to about 400 seconds Saybolt Universal viscosity at 100 F. with from about 6 to about 9 pounds, and preferably from about 7 to about 8 pounds of concentrated sulfuric acid, preferably fuming sulfuric acid, per gallon of oil.

The method of obtaining these desirable soaps of preferentially oil-soluble sulfonic acids derived from petroleum oils is illustrated by the following example, which describes the preparation of a sodium soap.

A petroleum oil distillate having a Saybolt Universal viscosity at 100 F. of from about 200 seconds to about 850 seconds is treated with from about '7 to about 8 pounds of fuming sulfuric acid per gallon of. oil in one-half pound increments or dumps. After the acid sludge from each one-half pound acid dump" is settled and withdrawn, the next one-half pound of fuming sulfuric acid isadded to the oil. The temperature of the oil before the fuming acid is added thereto is maintained below about 60 F. but due to the heat of reaction upon the addition of the sulfuric acid, the temperature of the oil may rise to from about F. to about F. After the required total amount of fuming sulfuric acid has been added to the oil and the oil freed of acid sludge. the acid treated oil containing oil-soluble sulfonic acids dissolved therein, is neutralized with a solution of sodium hydroxide. The aqueous alkali solution is then separated from the oil solution containing dissolved therein sodium soap of sulfonic acids and the latter then separated from the oil by extraction with alcohol of about 60% strength. The alcohol layer containing dissolved sodium sulfonates is then separated from the oil and subsequently distilled to recover the alcohol and remove water. The crude sulfonic soap obtained in this manner contains from about 30% to about 60% sodium sulfonate, from about 30% to about 60% oil, from about 1% toabout 10% Water. and up to 10% of inorganic salts which may be removedby the procedure hereinafter described.

The above procedure may be modified after the acid sludge is removed from the acid treated oil. The oil containing dissolved sulfonic acids is extracted with about 60% alcohol to remove the sulfonic acids which may then be neutralized with sodium hydroxide and subsequently freed of the alcohol by distillation.

, The crude soaps of these preferentially oilsoluble sulfonic acids obtained by the procedure described above may be freed of inorganic salts by purification. This Purification is preferably accomplished by dilution of the crude soap with fromabout /2 to about 10 parts, preferably 1 to 2 parts of 50% or higher strength alcohol, preferably alcohol of 60 to 70% strength,'and allowing the salts to settle while maintaining the mixture within the temperature rangeof to 175 F., preferably to F. 'When the salts have settled the supernatant alcohol-soap layer is separated and the alcohol is recovered by conventional distillation procedure. By this method of purification the salt content of the crude sulfonic soap can be readily reduced to 5% or less, e. g., to about 3.5%.

Suitable soaps of preferentially oil-soluble petroleum'sulfonic acids include those of metals in groups I, II, III, IV, VI and VIII of the periodic table. Thus, for example, I can employ the sodium, potassium, lithium, calcium, barium, tin, lead, aluminum, chromium, cobalt and nickel soaps of preferentially oil-soluble petroleum sulfonic acids. I can also employ the ammonium, alkylamonium and alkylolamine soaps of preferentially oil-soluble petroleum sulfonic acids. It is not intended to imply that the wide variety of sulfonates mentioned above are exactly equivalent for the purpose of my corrosion preventive lubricatin compositions. Because of their relative cheapness and high emcacy I prefer to use the sodium soaps, especially the sodium soaps of the preferred mahogany acids whose preparation has been described above. I have also found calcium soaps to be highly desirable.

The exact proportion of petroleum sulfonate to be used in my corrosion preventive lubricating compositions will vary with the particular sulfonate chosen for use and upon the severity of the service conditions which are anticipated. In general, I have found that a useful range of petroleum suifonate is about 5% to about 40%,

the actual sulfonate soap content being in the' range of about 2 to about 20%.

I can use any one of a wide variety of hydrocarbon lubricating oils. The hydrocarbon lubricating oil can be a pure or relatively pure individual hydrocarbon or a definite hydrocarbon mixture, or the complex mixture of hydrocarbons which constitute the lubricating oils produced in conventional petroleum refining operations. The 'choice of the particular 01] to be used will depend on the viscosity desired and the lubricating qualities of the oil and the viscosity desired in the corrosion preventive lubricating composition. In general, I can satisfactorily use petroleum lubricating oils having a viscosity in the range of about 40 to about 150 seconds Saybolt Universal at 210 F.

Although slushing compounds which have previously been prepared by compounding mahagony sulfonates with mineral oils afford some measure of protection against corrosion on metal surfaces and exhibit the first three of the four properties mainly desired in corrosion preventive lubricating compositions; as described above, they fail completely to neutralize acid products, such as acidic products of combustion inintemal combustion engines.

A typical composition which I can apply as a corrosion preventive lubricant comprises:

- Per cent Castor oil 2' Sodium mahogany soap 30 Hydrocarbon lubricating oil (viscosity 47 seconds Saybolt Universal at 210 F.) 61 Hydrocarbon lubricating oil (viscosity 94 seconds Saybolt Universal at 210 F.) 7

Weight,

Per cent Calcium mahogany soap 8.5 Castor oil 0.5

Hydrocarbon oil (viscosity between 165 and 175 seconds Saybolt Universal at 100 F.) 91.0 Phenyl alpha-naphthylamine 0.05 Pourex pour point depressant 0.5 Paranox 441 antioxidant 0.2

and

Calcium mahogany soap 1 5.0 Sodium mahogany soap 2 5.0 Castor oil 0.5

130 F.) 49.5 Phenyl alpha-naphthylamine 0.15 Paranox 441 antioxidant 0.2

1 The mahogany soap was of the type prepared by treating a petroleum distillate-having a viscosity in the range of to 300 seconds Saybolt between 3 and 5 pounds of strong, preferably fuming, sulfuric acid per gallon of distillate.

5 The mahogany soap was of the type prepared by treating a petroleum distillate having a viscosity between about 200 and about 850 seconds Sa bolt Universal at F. with between 7 and 8pound s 0 strong, preferably fuming, sulfuric acid per gallon of distillate.

Pourex pour point depressant is an alkylated naphthalene prepared by the chemical con-' densation of naphthalene with a chlorinated paramn wax in the presence of a Friedel-Crafts catalyst, e. g., as described in the following United States patents:

Patent No. Patentee Patent date June 19,1934 June 19,1034 Feb. 11,1936 Oct. 13,1936 Aug. 10,1037

1,963,917... F. H. MacLaren 1,963,918 do 2,030,307 '.do 2,057,104..." F. H. MacLaren and T. E. Stockdale- 2,080,655-. F. H. MacLaren Paranox 441 is a diisobutyl phenol.

A general rust preventive oil in accordance with this invention was prepared, having the following formula:

Weight, Per cent Purified sodium mahogany soap 5.5 011 soluble castor oil 5.5 Pourex pour point depressant 0.35

Hydrocarbon oil (viscosity between 50 and 57 seconds Saybolt Universal at 100 F.) 89.0

The oil soluble castor oil employed in the above formula was a commercial product produced by the W. C. Hardesty Co., Inc. Castor oil may be rendered more soluble in hydrocarbon oils by a variety of processes, e.' g., by adding a small amount of a camphor sulfonic acid thereto, by catalytically esterifying a fraction of the hydroxyl groups in castor oil with various acid radicals. e. g. oleate, stearate, and the like, or by partial dehydration of castor oil with dehydration catalysts, e. g. PC]: and the like. It should be understood that-the term "castor oil in the appended claims is intended also to include castor oils modified to increase their solubilities in hydrocarbon oils.

I have found that a useful adjunct to my corrosion preventive lubricating composition is a small proportion of p,p'-tetramethyldiaminodiphenylmethane. The addition of this compound in proportions of about 0.1 to 2% enhances the performance of my corrosion preventive lubricating compositions, especially in humid atmospheres and in salt air or sea water.

In addition, I can add polymeric thickeners, viscosity index improvers, oiliness agents, pour point depressants, antioxidants for castor compounds, antioxidants for hydrocarbon oils, etc.,

my corrosion preventive lubricating composions.

Universal at 100 F. with tection of metal surfaces, as in gun barrels. metal containers for petroleum products or other corrosive materials, idle machinery, finished machine parts and accessories in storage, stand-by or emergency equipment, etc.

I claim:

1. A composition of matter comprising about to about 40% of a soap of a preferentially oilsoluble petroleum sulfonic'acid, about 0.5% to about of a castor compound selected from the group consisting of castor oil, castor amide and glycerol monoricinoleate, and a major proportion of a hydrocarbon lubricating oil."

2. A composition of matter comprising about 5% to about 40% of a soap of a preferentially oil-soluble petroleum sulfonic acid, about 0.5% to about 10% of castor oil, and a major proportion of a hydrocarbon lubricating oil.

3. A composition of matter comprising about 5% to about 40% of a soap of a preferentially oil-soluble petroleum sulfonic acid, about 0.5% to about 10% of castor amide, and a major proportion of a hydrocarbon lubricating oil.

4. A composition of matter comprising about 5% to about 40% of a soap of a preferentially oil-soluble petroleum sulfonic acid, about 0.5% to about 10% of glycerol monoricinoleate, and a major proportion of a hydrocarbon lubricating oil.

5. A composition of matter comprising about 5% to about 40% of a soap of a preferentially oil-soluble sulfonic acid produced by treating a petroleum distillate having a viscosity in the range of about 50 to about 1000 seconds Saybolt Universal at 100 F. with from about 6 to about 9 pounds of strong sulfuric acid per gallon of said distillate, about 0.5% to about 10% of a castor compound selected from the group consisting of castor oil, castor amide and glycerol monoricinoleate, and a major proportion of a hydrocarbon lubricating oil.'

6. A composition'of matter comprising about 5% to about 40% of a soap of a preferentially oil-soluble sulfonic acid produced by treating a petroleum distillate having a viscosity in the range of about 50 to about 1000 seconds Saybolt Universal at 100 F. with from about 6 to about 9 pounds of strong sulfuric acid per gallon of said distillate, about 0.5% to about 10% of castor oil and a major proportion of hydrocarbon lubricating oil.

. '7. A composition of matter comprising about 5% to about 40% of a soap of a preferentially oil-soluble sulfonic acid produced by treating a petroleum distillate having a viscosity in the range of about 50 to about 1000 seconds Saybolt Universal at 100 F. with from about 6 to about 9 pounds of strong sulfuric acid per gallon of said distillate, about 0.5% to about 10% of a castor amide, and a major proportion of hydrocarbon lubricating oil.

8. A composition of matter comprising about 5% to about 40% of a soap of a preferentially oil-soluble sulfonic acid produced by treating a petroleum distillate having a viscosity in the range of about 50 to about 1000 seconds Saybolt Universal at 100 F. with from about 6 to about 9 pounds of strong sulfuric acid per gallon of said distillate, about 0.5% to-about 10% of glycerol monoricinoleate and a major proportion of hydrocarbon lubricating oil.

9. A composition of matter comprising about 5% to about 40% of a sodium soap of a preferentially oil-soluble sulfonic acid produced by treating a petroleum distillate having a viscosity in the range of about 50 to about 1000 seconds Saybolt Universal at F. with from about 6 to about 9 pounds of strong sulfuric acid per gallon of said distillate, about 0.5% to about 10% of a castor compound selected from the group consisting of castor oil, castor amide and glycerol monoricinoleate, and a major proportion of hydrocarbon lubricating oil.

10. A composition of matter comprising about 5% to about 40% of a sodium soap of a preferentially oil-soluble sulfonic acid produced by treating a petroleum distillate having a viscosity in the range of about 50 to about 1000 seconds Saybolt Universal at 100 F. with from about 6 to about 9 pounds of strong sulfuric acid per gallon of said distillate, about 0.5% to about 10% of castor oil and a major proportion of hydrocarbon lubricating oil.

11. A composition of matter comprising about 5% to about 40% of a sodium soap of a preferentially oil-soluble sulfonic acid produced by treating a petroleum distillate having a viscosity in the range of about 50 to about 1000 seconds Saybolt Universal at 100 F. with from about 6 -to about 9 pounds of strong sulfuric acid per gallon of said distillate, about 0.5% to about 10% of castor amide and a major proportion of hydrocarbon lubricating oil.

12. A composition of matter comprising about 5% to about 40% of a sodium soap of a preferentially oil-soluble sulfonic acid produced by treating a petroleum distillate having a viscosity in the range of about 50 to about 1000 seconds Saybolt Universal at 100 F. with from about 6 to about 9 pounds of ,strong sulfuric acid per gallon of said distillate, about 0.5% to about 10% of glycerol monoricinoleate and a major proportion of hydrocarbon lubricating oil.

13. A composition of matter comprising about 5% to about 40% of a calcium soap of a preferentially oil-soluble petroleum sulfonic acid, about 0.5% to about 10% of a castor compound selected from the group consisting of castor oil, castor amide and glycerol monoricinoleate, and a major proportion of a hydrocarbon lubricating oil.

14. A composition of matter comprising about 5% to about 40% of a calcium soap of a preferentially oil-soluble petroleum sulfonic acid, about 0.5% to about 10% of castor oil, and a major proportion of a hydrocarbon lubricating oil.

15. A composition of matter comprising about 5% to about 40% of a calcium soap of a preferentially oil-soluble petroleum sulfonic acid, about 0.5% to about 10% of castor amide, and a major proportion of a hydrocarbon lubricatingoil.

16. A composition of matter comprising about 5% to about 40% of a calcium soap of a preferentially oil-soluble petroleum sulfonic acid, about 0.5% to about 10% of glycerol monoricinoleate,

and a major proportion of a hydrocarbon lubri-- eating oil.

17. A composition of matter comprising about 5% to about 40% of a sodium soap of a preferentially oil-soluble petroleum sulfonic acid, about 0.5% to about 10% of a castor compound selected from the group consisting of castor oil, castor amide and glycerol monoricinoleate, and a major proportion of a hydrocarbon lubricating oil.

18. A composition of matter comprising about 5% to about 40% of a sodium soap of a preferentially oil-soluble petroleum sulfonic acid, about 9 10 0.8% to about 10% of castor oil. and a major 20. A composition of matter comprising about proportion 01' a hydrocarbon lubricating oil. 5% to about 40% of a sodium soap or a preter- 19. A composition of matter comprising about entiaily oil-soluble petroleum sulfonic acid, about 5% to about 40% of a sodium soap of a prefer- 0.5% to about 10% of glycerol 'monoricinoleate, entially oil-soluble petroleum sulfonic acid. about s 1 and a major proportion of a hydrocarbon lubri- 0.5% to about 10% of castor amide. and a major eating oil. proportion of a hydrocarbon -lubricating oil. MURRAY L. SCHWARTZ. 

